A contact is a semiconductor chip-to-package interconnect technology. The advantages in the contacts lie in the extendibility to finer pitch and the superior electromigration (EM) performance. The contacts may be made from copper and the finer pitch is due to the contact's vertical sidewall.
In traditional copper contact technology, a small amount of solder is still required to connect the copper contacts of the chip to the receiving pads. Sometimes, as shown in FIG. 1, the solder may wet the upper surface and sidewall of the contact. In some applications contact wetting may be beneficial. For example, in implementations where solder is attached a receiving pad of a substrate or carrier, the contact may include wettable surfaces to ensure adequate electrical connection between the chip and package.
Chip fabrication processes typically require an application of adhesive to the wafer subsequent to formation of various contacts. For example, a handler is attached to the contact side of a wafer using an adhesive. In subsequent chip fabrication process the adhesive is removed from the chip wafer. In some instances, traditional copper contacts react poorly with the adhesive resulting in non-wettable surfaces.